To the Editor.—
The inhibitory action of the tetracyclines on human protein synthesis has been clearly elucidated,1 and it is well known that these antibiotics may create an elevated blood urea nitrogen (BUN) level, particularly in patients with decreased renal function.2,3 However, the fact that diuretics may also elevate the BUN was alluded to, but not clearly implicated. Kleit et al4 explains that the phenomenon may occur by two mechanisms: a decrease in glomerular filtration rate and an increased reabsorption of filtered urea. Clearly, if one utilizes two agents with the ability to produce increased BUN levels, a rise would be expected more frequently, as well as being of greater magnitude than when one of the drugs was utilized by itself.Finally, one of the newer congeners of tetracycline, doxycycline, has been heralded as being the only member of that group which does not produce rises in
Alexander MR. Tetracycline and Rises in Urea Nitrogen. JAMA. 1972;221(7):713–714. doi:10.1001/jama.1972.03200200059023
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